Most dairy cattle are bred using conventional artificial insemination (AI) techniques resulting in conception rates of approximately 20-40%. Frozen semen straws are used in conventional AI techniques, each holding approximately 20 million unsorted sperm. In comparison, a bull in a pasture deposits billions of sperm each time he mates with a cow or a heifer. Further, the bull is not shy about repeatedly mating with a female while she is in heat, further increasing the enormous number of sperm and the large volume of semen in the reproductive system of a female bovine.
Dairy cattle bulls have been bred to sire females that produce the most milk. These desirable bulls are developed and raised on ranches that are typically referred to in the industry as “Bull Studs”. The dairy industry is very picky about the genetics of the bulls which produce the sperm used in conventional semen straws. Semen from these desirable bulls is collected at the Bull Stud and packaged in the frozen semen straws for sale to cattle owners and others. In 2010, there were approximately 25-30 Bull Studs in the U.S. producing frozen semen straws for the dairy and beef industry. But market demand for semen straws from the top bulls exceeds the natural supply. (A bull can only produce so much sperm during the course of a year.)
Intuitively, a reduction in the number of sperm in a semen straw would lower conception rates using conventional AI techniques. But, the inventor has developed a new technique to reduce the number of sperm required for impregnation of a female while at least maintaining conception rates comparable to conventional AI techniques (approximately 20-40% in dairy cattle). As a result, the Bull Studs may sell more semen straws over time from a single bull with superior genetics. This could allow dairymen to breed more of their cows with sperm from the most desirable bulls.
Some bovine semen is sex sorted. Current sex sorting technology is relatively slow. Therefore, sex-sorted straws contain a fraction of the number of sperm found in a conventional unsorted semen straw. For example, to deliver a straw with a 90% female offspring expectation it is current practice to place a minimum of 2.1 million sorted sperm in a straw. In addition, sorted semen may contain more sperm but have a reduced female offspring expectation. The speed of the sorting process is inversely related to the accuracy of the machine's ability to sort by sex. (The faster the machine sorts, the less accurate it becomes in determination of the sex of the semen.) In the case of sex-sorted semen, the minimum number of sperm suitable for use in conventional AI techniques is 2.1 million sperm with a 90% female offspring expectation; although this number is subject to change if the sorting technology improves. Using the present invention, less than 2.1 million sex-sorted sperm will be suitable for artificial insemination of a female, with a 90% female offspring expectation. Sex sorted sperm are not always packaged in a straw with 2.1 million sperm.
Over the years, Brad Stroud, DVM has been trying to develop ways to increase conception rates in the dairy and beef industry. Two prior U.S. patent applications filed by Dr. Stroud aim to increase the overall conception rates of beef and dairy cattle: “Artificial Breeding Techniques for Bovines including Semen Diluents and AI Apparatus” Ser. No. 11/829,240 filed on Jul. 27, 2007 and “Artificial Breeding Techniques for Bovines Including Semen Diluents and AI Apparatus” Ser. No. 12/506,723 filed on Jul. 21, 2009. These two prior patent applications used conventional frozen semen straws containing approximately 20 million sperm and sex sorted semen. Neither of these two prior patent applications addressed the shortage of sperm from desirable bulls. These two prior patent applications claim to increase conventional conception rates of cattle that have been artificially inseminated using the methods disclosed therein.
In contrast, the present patent application, also by Dr. Stroud, does not promise increased conception rates. Instead, the present invention offers conception rates that are at least comparable to conventional AI techniques (For example, approximately 20-40% in dairy cattle). The present invention will significantly reduce the number of sperm from desirable bulls used in each semen straw, allowing more cows to take advantage of a precious resource that is limited by natural production.
Conventional artificial insemination devices are well known to those skilled in the art, such as the prior art AI device shown in FIG. 1 herein. FIG. 1 is not to scale and is for illustrative purposes only for a reader that has never seen the actual apparatus. This metal and plastic AI device has a non-disposable hollow metal barrel with a metal plunger sliding to and fro inside the hollow metal barrel and a disposable plastic sheath. The distal end of the barrel has a receptacle sized to receive a semen straw. Conventional semen straws are crimped on one end and have a cotton plug in the other end. To use the semen straw with the prior art AI instrument of FIG. 1, the straw is warmed and then the crimped end is cut. The cotton plug end of the semen straw is placed in the receptacle of the conventional prior art AI device. The metal plunger contacts the cotton plug.
This prior art metal and plastic non-disposable AI device and the semen straw are inserted into a disposable elongate plastic sheath. For this reason the conventional AI instrument in FIG. 1 is referred to as a “metal and plastic” apparatus. In this conventional AI instrument, the cut end of the semen straw engages the plastic sheath, forming a seal to prevent semen leaks. Prior art sheaths of this design are well known to those skilled in the art. This prior art metal and plastic device is inserted into cow's reproductive organs. No diluent is used. Then the AI Technician pushes on the metal plunger which pushes the cotton plug through the semen straw and forces the semen out of the tip of the AI device. The cotton plug is not injected into the cow because it is trapped by the seal on the plastic sheath. But the cotton plug does absorb some of the semen which is lost and not able to fertilize the female. The present invention has a more simple solution, with a disposable non-toxic syringe connected to an elongate, metal, single use pipette, portions of which are inserted into the cow's reproductive organs.
The single use AI instrument of the present invention is about 18 inches long, with an od of about 0.134 inches (3.4 mm) which is much easier to pass through the cervix of a heifer than the prior art metal and plastic AI instrument. The elongate metal device of the present invention is hollow and there is no plunger like the conventional prior art AI instrument. The AI device of the present invention does not require a plastic sheath, like the prior art.
The prior art metal and plastic AI device in FIG. 1 is used with a plastic sheath to keep the device sterile. Therefore, this conventional metal AI device can be used over and over by continually replacing the sheath for each cow. The prior art metal and plastic AI device does not use diluent; it only injects semen. The prior art metal and plastic AI device uses a disposable plastic sheath and therefore the metal part of the apparatus can be used over and over with different cows. In other words, the disposable plastic sheath keeps the metal part of the apparatus clean and able to be reused. In stark contrast, the metal pipette in the AI device of the present invention is contaminated on the outside by direct contact with the cow's reproductive tract and on the inside by the reduced sperm count semen. Therefore, the metal pipette of the present invention is contaminated after a single use and cannot be reused like a prior art metal and plastic AI device.
Some bovine AI Technicians will sometimes try to inseminate several females with a single conventional semen straw, especially to save money. In the U.S. dairy industry especially, Bovine AI Technicians will sometimes try to inject only a portion of a conventional straw in a female. This technique is thought to result in lower conception rates than the conventional rates discussed herein. This prior art technique warms one conventional straw at a time. The portions of the semen not used in the first female must be used in a second female within about 20 minutes after thaw.
U.S. Pat. No. 5,147,299 to Mendoza uses an illuminated vaginal speculum to insert an AI device. The second Mendoza patent, (U.S. Pat. No. 6,071,231) explains that the techniques taught in the first patent produce low conception rates. The teachings of the second Mendoza patent were apparently designed to increase conception rates over the teachings in the first Mendoza patent.
U.S. Pat. No. 6,071,231 to Mendoza is entitled “Device and Method for Artificial Insemination of Bovines and other Animals” ('231 Patent). This device is best seen in FIG. 6 of the '231 Patent drawings. The '231 Patent requires two syringes, and a balloon catheter. An illuminated vaginal speculum is used to allow visual insertion into the cow's reproductive organs; rather than rectal palpation. The present invention does not require an illuminated vaginal speculum for insertion into the cow. Instead, the AI apparatus of the present invention is inserted using rectal palpation.
In simple terms, the apparatus in the '231 Patent is inserted by sight, thus the need for an illuminated speculum, whereas the present invention is inserted by “feel”. The first Mendoza syringe is used to inflate and deflate the balloon catheter. The second Mendoza syringe is used to inject a diluent for the purpose of pushing semen into the cow, as best seen in FIG. 3 herein. The present invention uses one syringe instead of two because the present invention does not need a balloon catheter. Because of this construction, the present invention is sometimes referred to “catheter free”. The '231 Patent teaches use of a diluent such as 2.9% sodium citrate solution. The '231 Patent recommends optimum amounts of semen and diluent for various sized animals; but the patent is silent on the volume of diluent for any animal. Because the '231 Patent is so cumbersome and requires the use of two syringes and a balloon catheter, it is not in wide use. The present invention has a more elegant arrangement, with a single disposable non-toxic syringe connected to an elongate, metal, single use pipette.
U.S. pending patent applications Ser. Nos. 11/829240 and 12/506,723 to Stroud disclose a disposable syringe connected to an elongate plastic pipette. The plastic pipette must be rigid enough to allow a Technician to guide it through the three rings of the cervix, which requires a skilled Bovine AI Technician, especially in the case of a heifer. Without enough stiffness in the plastic pipette, the Technician a) may lose his/her ability to properly guide the pipette and potentially injures a valuable animal, b) can also result in incorrect placement of the semen in the reproductive tract and/or c) may also lose the ability to pass the pipette through the cervix. Production of an elongate plastic pipette as imagined in Stroud '723 has been problematic. Therefore, the present invention discloses a single use, metallic, elongate pipette which does have sufficient stiffness to allow a Technician to properly guide the device through the three rings of the cervix. Unlike Stroud '240 and '723, which imagined development of a disposable plastic pipette, the present invention uses a metal pipette to help guide the device through the cow's reproductive organs without injury to the cow or unnecessary delay in the procedure. Stroud '240 and '723 also failed to recognize that some syringes are toxic to sperm and further, that some storage conditions could enhance or create toxicity in a syringe. The present invention uses non-toxic syringes.
The present invention has several advantages as follows: First, the present invention uses a disposable, non-toxic syringe, unlike any of the prior art. Second, the present invention has a small od, unlike any of the prior art which makes it easier to insert into heifers. Third, the present invention uses semen with a reduced sperm count, unlike some of the prior art. Fourth, the present invention uses a stiff metal pipette which facilitates insertion, unlike Stroud which imagined a plastic pipette and unlike the conventional prior art AI instrument which uses a metal and plastic pipette.